diff --git a/libuavcan/include/uavcan/util/templates.hpp b/libuavcan/include/uavcan/util/templates.hpp
index cb4e373004..4295c08d16 100644
--- a/libuavcan/include/uavcan/util/templates.hpp
+++ b/libuavcan/include/uavcan/util/templates.hpp
@@ -5,6 +5,7 @@
 #pragma once
 
 #include <climits>
+#include <cstddef>
 #include <cmath>
 #include <uavcan/impl_constants.hpp>